If the OP is considering to keep the car NA, he can always go to Dinan and put I believe the 3.62 diff that they offer. It makes a huge difference with the down low torque. I come from an 6sp M3 and I have the 4.10 diff and it is a tremendous improvement for day to day city driving. With DCT diff from Dinan it provides even better improvement from the lower RPMs and will always keep the car in the rev range where the power will be.
Before I put the stroker in my M3 this was the best improvement I have ever done to the car for day to day drivability.
Of course you lose some of the top speed, but rarely do I get the chance to WOT the vehicle to those speeds daily.
Just a suggestion OP.